U.S. patent application number 13/625889 was filed with the patent office on 2013-03-28 for semiconductor structure including guard ring.
This patent application is currently assigned to INFINEON TECHNOLOGIES AG. The applicant listed for this patent is Infineon Technologies AG. Invention is credited to Martin Kerber, Matthias Stecher.
Application Number | 20130075861 13/625889 |
Document ID | / |
Family ID | 47828075 |
Filed Date | 2013-03-28 |
United States Patent
Application |
20130075861 |
Kind Code |
A1 |
Kerber; Martin ; et
al. |
March 28, 2013 |
Semiconductor structure including guard ring
Abstract
One or more embodiments relate to a semiconductor structure,
comprising: a conductive feature; an outer guard ring; and an inner
guard ring between the outer guard ring and the conductive feature,
the inner guard ring being electrically coupled to the conductive
feature.
Inventors: |
Kerber; Martin; (Pettneu am
Arlberg, AT) ; Stecher; Matthias; (Muenchen,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Infineon Technologies AG; |
Neubiberg |
|
DE |
|
|
Assignee: |
INFINEON TECHNOLOGIES AG
Neubiberg
DE
|
Family ID: |
47828075 |
Appl. No.: |
13/625889 |
Filed: |
September 25, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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13245891 |
Sep 27, 2011 |
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13625889 |
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Current U.S.
Class: |
257/531 ;
257/532; 257/E27.018; 257/E27.024 |
Current CPC
Class: |
H01L 2224/04042
20130101; H01L 2224/04042 20130101; H01L 29/402 20130101; H01L
24/05 20130101; H01L 2224/48463 20130101; H01L 2924/3025 20130101;
H01F 27/2804 20130101; H01L 23/5227 20130101; H01L 2224/48465
20130101; H01L 23/585 20130101; H01L 2224/05553 20130101; H01L
2924/00 20130101; H01L 2924/00 20130101; H01L 2224/02166 20130101;
H01L 2924/3025 20130101 |
Class at
Publication: |
257/531 ;
257/532; 257/E27.024; 257/E27.018 |
International
Class: |
H01L 27/06 20060101
H01L027/06 |
Claims
1. A semiconductor structure, comprising: a conductive feature; an
outer guard ring; and an inner guard ring between said outer guard
ring and said conductive feature, said inner guard ring being at
the same voltage as said conductive feature.
2. The structure of claim 1, wherein said outer guard ring at least
partially encircles said conductive feature.
3. The structure of claim 1, wherein said inner guard ring at least
partially encircles said conductive feature.
4. The structure of claim 1, wherein said conductive feature is
part of a final metallization level.
5. The structure of claim 1, wherein said conductive feature is a
conductive coil.
6. The structure of claim 1, wherein said conductive feature is a
transformer, said transformer including an upper coil over a lower
coil.
7. The structure of claim 1, wherein said inner guard ring is part
of a final metallization level.
8. The semiconductor structure of claim 1, wherein said outer guard
ring is proximate the periphery of said semiconductor
structure.
9. The structure of claim 1, wherein said conductive feature is
embedded in a dielectric layer, said dielectric layer including a
contaminated portion between said outer guard ring and said
conductive feature.
10. The structure of claim 9, wherein said inner guard ring is
positioned so that there is substantially no lateral electric field
through said contaminated portion.
11. The structure of claim 9, wherein said inner guard ring is
between said outer guard ring and said contaminated portion.
12. The structure of claim 9, wherein a resistivity of said
contaminated portion is less than a resistivity of a
non-contaminated portion of said dielectric layer.
13. A semiconductor structure, comprising: a conductive feature; an
outer guard ring; and an inner guard ring between said outer guard
ring and said conductive feature, said inner guard ring being
electrically coupled to said conductive feature.
14. The structure of claim 13, wherein said outer guard ring at
least partially encircles said conductive feature.
15. The structure of claim 13, wherein said inner guard ring at
least partially encircles said conductive feature.
16. The structure of claim 13, wherein said conductive feature is
part of a final metallization level.
17. The structure of claim 13, wherein said conductive feature is a
conductive coil.
18. The structure of claim 13, wherein said conductive feature is a
transformer, said transformer including an upper coil over a lower
coil.
19. The structure of claim 13, wherein said inner guard ring is
part of a final metallization level.
20. The semiconductor structure of claim 13, wherein said outer
guard ring is proximate the periphery of said semiconductor
structure.
21. The structure of claim 13, wherein said conductive feature is
embedded in a dielectric layer, said dielectric layer including a
contaminated portion between said outer guard ring and said
conductive feature.
22. The structure of claim 21, wherein said inner guard ring is
positioned so that there is substantially no lateral electric field
in said contaminated portion.
23. The structure of claim 21, wherein said inner guard ring is
positioned so that there is substantially no current in said
contaminated portion.
24. The structure of claim 21, wherein said inner guard ring is
between said outer guard ring and said contaminated portion.
25. The structure of claim 21, wherein a resistivity of said
contaminated portion is less than a resistivity of a
non-contaminated portion.
26. A semiconductor structure, comprising: a dielectric layer, said
dielectric layer having a contaminated portion; a conductive
feature disposed in said dielectric layer, said conductive feature
being at a first voltage; and an outer guard ring disposed in said
dielectric layer, said outer guard ring being at a second voltage
different from said first voltage, wherein there is substantially
no lateral electric field within said contaminated portion.
27. The structure of claim 26, further comprising an inner guard
ring between said outer guard ring and said contaminated
portion.
28. The structure of claim 26, wherein said outer guard ring at
least partially encircles said conductive feature.
29. The structure of claim 26, wherein said inner guard ring at
least partially encircles said conductive feature.
30. The structure of claim 26, wherein said conductive feature is
part of a final metallization level.
31. The structure of claim 26, wherein said conductive feature is a
conductive coil.
32. The structure of claim 26, wherein said conductive feature is a
transformer, said transformer including an upper coil over a lower
coil.
33. The structure of claim 26, wherein said inner guard ring is
part of a final metallization level.
34. The structure of claim 26, wherein said contaminated portion
has a resistivity less than a remaining portion of said dielectric
layer.
35. A semiconductor structure, comprising: a dielectric layer, said
dielectric layer having a corrupted portion; a conductive feature
disposed in said dielectric layer, said conductive feature being at
a first voltage; and an outer guard ring disposed in said
dielectric layer, said outer guard ring being at a second voltage
different from said first voltage, wherein there is substantially
no lateral electric field proximate said conductive feature.
36. The structure of claim 1, wherein said conductive feature is a
capacitor.
37. The structure of claim 1, wherein said conductive feature is a
capacitor, said capacitor including an upper capacitor plate over a
lower capacitor plate.
38. The structure of claim 13, wherein said conductive feature is a
capacitor.
39. The structure of claim 13, wherein said conductive feature is a
capacitor, said capacitor including an upper capacitor plate over a
lower capacitor plate.
40. The structure of claim 26, wherein said conductive feature is a
capacitor.
41. The structure of claim 26, wherein said conductive feature is a
capacitor, said capacitor including an upper capacitor plate over a
lower capacitor plate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation-in-part
application of U.S. application Ser. No. 13/245,891 filed Sep. 27,
2011, now pending, the entirety of which is herein incorporated by
reference.
FIELD OF THE INVENTION
[0002] One or more embodiments of the present invention relate to
semiconductor structures.
BACKGROUND
[0003] Coreless transformers, which may be composed of a bottom
coil and a top coil, provide an attractive option for conventional
CMOS process flow to fabricate products with bi-directional signal
flow as used for controlling power switches at high voltage (for
example, greater than 200 volts) in DC-DC converters and control of
electric drives. The dielectric isolation strength to sustain the
high operating voltage and robustness against very high voltage
surges in particular, may be one of the limiting reliability
problems. Frequently the high voltage robustness of such products
may be much lower than expected from bulk material properties and
the isolation distances defined by the thickness of the isolating
layers and the layout and the product. After a dielectric breakdown
a low ohmic conductive path may be formed between the top coil
(which may be a point of high potential) and the guard ring (which
may be at ground potential). Since high voltage isolation
properties (for example, greater than 6,000 volts) are difficult to
study experimentally, little is known about processing and
environmental conditions affecting the dielectric isolation
strength.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 shows a semiconductor structure in accordance with an
embodiment;
[0005] FIG. 2 shows a semiconductor structure in accordance with an
embodiment;
[0006] FIG. 3 shows a semiconductor structure in accordance with an
embodiment;
[0007] FIG. 4 shows a semiconductor structure in accordance with an
embodiment;
[0008] FIG. 5 shows a semiconductor structure in accordance with an
embodiment;
[0009] FIG. 6 shows a semiconductor structure in accordance with an
embodiment;
[0010] FIGS. 7A and 7B show a conductive feature in accordance with
an embodiment;
[0011] FIG. 8 shows a semiconductor structure in accordance with an
embodiment;
[0012] FIGS. 9A, 9B and 9C show a semiconductor structure in
accordance with an embodiment;
[0013] FIG. 10 shows a semiconductor structure in accordance with
an embodiment.
DESCRIPTION
[0014] The following detailed description refers to the
accompanying drawings that show, by way of illustration, specific
details and embodiments in which the invention may be practiced.
These embodiments are described in sufficient detail to enable
those skilled in the art to practice the invention. Other
embodiments may be utilized and structural, logical, and electrical
changes may be made without departing from the scope of the
invention. The various embodiments are not necessarily mutually
exclusive, as some embodiments can be combined with one or more
other embodiments to form new embodiments.
[0015] FIG. 1 shows a semiconductor structure 1010. The
semiconductor structure is an embodiment. The semiconductor
structure 1010 may, for example, represent a portion of a
semiconductor chip and/or a semiconductor device. The semiconductor
structure 1010 includes a substrate 210. The substrate 210 may be
any semiconductor substrate. The semiconductor substrate may be a
silicon substrate. For example, the substrate may be a bulk
semiconductor substrate or a silicon-on-insulator substrate. A bulk
semiconductor substrate may include an epitaxial layer or may be
made without an epitaxial layer.
[0016] The structure 1010 includes metallization levels M1, M2, M3
and MF. MF represents the final or top metallization level of the
semiconductor structure. More generally, in other embodiments, the
structure 1010 may include one or more metallization levels such as
a plurality of metallization levels. The metallization levels may
include a final or top metallization level MF.
[0017] Each of the metallization levels may include one or more
conductive lines. For example, a metallization level may include a
plurality of conductive lines. The conductive lines may be spacedly
disposed from each other. In an embodiment, two or more conductive
lines may be electrically isolated from each other. In one or more
embodiments, two or more conductive lines may be electrically
coupled together. In one or more embodiments, a conductive line may
be useful for conductive electrical signals primarily in a
horizontal direction. A conductive line may include or may be a
conductive pad.
[0018] Referring to FIG. 1, it is seen that the structure 1010
includes a conductive line M11 which is part of the first
metallization level M1, a conductive line M21 which part of the
metallization level M2, a conductive line M31 which is part of the
metallization level M3 and a first final conductive line MF1 which
is part of the final metallization level MF. The conductive line
M11 is embedded in an interlevel dielectric layer ILD1. The
conductive line M21 is embedded in an interlevel dielectric layer
ILD2. The conductive line M31 is embedded in an interlevel
dielectric layer ILD3. The conductive line MF1 is embedded in a
dielectric layer DF. In one or more embodiments, a conductive line
may be a metallic line.
[0019] Conductive vias may also be part of the metallization
system. In one or more embodiments, a conductive via may be useful
for conducting electrical signals primarily in a vertical
direction. For example, the structure 1010 shown in FIG. 1,
includes conductive vias C11, V11, V21, and V31. The conductive via
C11 electrically couples the conductive line M11 to the substrate
210. The conductive via V11 electrically couples the conductive
line M11 to the conductive line M21. The conductive via V21
electrically couples the conductive line M21 to the conductive line
M31. The conductive via V31 electrically couples the conductive
line M31 to the conductive line MF1. A conductive via may include a
metallic material.
[0020] In the embodiment shown, the conductive contact C11 is an
example of a conductive via that electrically couples the first
metallization level M1 to the substrate 210. The conductive contact
C11 is embedded in a dielectric layer 220. A conductive contact may
include a metallic material.
[0021] The structure 1010 includes interlevel dielectric layers
ILD1, ILD2 and ILD3. The final metallization level MF is embedded
in a dielectric layer DF.
[0022] The final metallization level MF may include one or more
conductive lines. The final metallization level MF may include a
plurality of spaced apart conductive lines. In one or more
embodiments, the conductive lines may be electrically isolated from
each other. A conductive line may, for example, transport current
in a horizontal direction. A conductive line may be or may include
a pad.
[0023] The structure 1010 may include a first guard ring GR1. The
first guard ring GR1 may also be an outer guard ring. The first
guard ring GR1 includes the conductive lines M11, M21, M31 and MF1.
The first guard ring GR1 includes the conductive vias V11, V21 and
V31. The first guard ring GR1 may be placed at a voltage VOLT1. The
voltage VOLT1 may be the ground voltage. In the embodiment shown,
the first guard ring GR1 is shown to be electrical coupled to the
substrate by way of the conductive via (e.g. conductive contact)
C11. However, in another embodiment, it need not be coupled to the
substrate 210.
[0024] In an embodiment, the first guard ring GR1 may at least
partially encircle the final conductive line MF2. In an embodiment,
the first guard ring GR1 may fully encircle the final conductive
line MF2. In an embodiment, the first guard ring GR1 may partially
encircle the final conductive line MF2.
[0025] In an embodiment, the first guard ring GR1 may at least
partially surround the final conductive line MF2. In an embodiment,
the first guard ring GR1 may fully surround the final conductive
line MF2. In an embodiment, the first guard ring GR1 may partially
surround the final conductive line MF2.
[0026] FIG. 1 shows a final metallization level MF that includes a
conductive line MF1 and a conductive line MF2. The conductive line
MF2 may be a conductive pad (for example, a lower conductive pad)
or may include a conductive pad. In the example shown in FIG. 1,
the conductive line MF2 may serve as a lower conductive pad. An
upper conductive pad 250 may be formed over the lower conductive
pad MF2. A conductive lead 310 may be disposed over the upper
conductive pad 310. The conductive lead 310 may provide electrical
communication with the outside world.
[0027] A dielectric layer 240 may be disposed over the final
metallization level MF. The dielectric layer 240 may for example,
include a stack of two or more layers 240A and 240B (wherein layer
240A and layer 240B may be viewed as sub-layer of layer 240). As an
example, a dielectric layer 240 may include a first dielectric
layer 240A and a second dielectric layer 240B overlying the first
dielectric layer 240A. The first dielectric layer 240A may be an
oxide layer such as a silicon oxide. The second dielectric layer
240B may be a nitride layer such as a silicon nitride.
[0028] A passivation layer 290 may be formed over the dielectric
layer 240. The passivation layer 290 may, for example, include a
polyimide.
[0029] An opening 292 may be formed through the passivation layer
290.
[0030] An opening 242 (for example, a pad opening) may be formed
through the dielectric layer 240 so as to expose the conductive
line MF2. An upper conductive pad 250 may then be formed within the
opening 242 and over the conductive line MF2. The upper pad 250 may
include at least one layer. In an embodiment, the upper pad 250 may
include a stack of two or more layers such as a stack of three or
more layers. In the embodiment shown, the upper pad 250 may include
a stack of three layers 250A, 250B and 250C. The layer 250A may
include NiP. The layer 250B may include the element Pd (palladium).
The Pd may be in the form of pure palladium and/or palladium alloy.
The layer 250C may include the element Au (gold). The Au may be in
the form of pure gold and/or gold alloy.
[0031] It is possible that the upper pad 250 may not overlie all of
the conductive line MF2. For example, the upper conductive pad 250
may not fill the lateral space of the opening 242. For example, it
is possible that a space 242A (e.g. a portion of the opening 242)
remains about at least a portion of the perimeter of the conductive
line MF2 (e.g. between the outer perimeter of the upper pad 250 and
the inner perimeter of the dielectric layer 240). In one or more
embodiments, the space 242A may at least partially encircle (for
example, laterally) the upper pad 250. In one or more embodiments,
the space 242A may partially encircle the upper pad 250. In one or
more embodiments, the space 242A may fully encircle the upper pad
250.
[0032] In one or more embodiments, the space 242A may at least
partially surround (for example, laterally) the upper pad 250. In
one or more embodiments, the space 242A may partially surround the
upper pad 250. In one or more embodiments, the space 242A may fully
surround the upper pad 250.
[0033] Contaminants (e.g. such as chemicals or moisture) may enter
the structure through the space 242A where the dielectric layer 240
is broken. The contaminants may pass through the space 242A and
diffuse along the interface between the final metallization level
MF and the dielectric layer 240 deeper into the system. For
example, the contaminants may diffuse along the interface between
the dielectric layer 240 and final metal line MF2. Or the
contaminants may move even deeper into the system by diffusing
along the interface between the dielectric layer 240 and the
dielectric layer DF.
[0034] The contaminants may, for example, degrade the electrical
isolation properties of the dielectric layer DF within a region DFC
(e.g. a contaminated region) of the dielectric layer DF. Hence, in
one or more embodiments, the contaminated region DFC may have
degraded or weakened dielectric properties. For example, it is
possible that the resistivity of the material of the contaminated
region DFC is less than the resistivity of the material of the
non-contaminated portion of the layer DF.
[0035] In one or more embodiments, the conductive line MF2 may be
placed at a voltage VOLT2 (perhaps by a lead 310). In an
embodiment, the voltage VOLT2 may be different from the voltage
VOLT1. In an embodiment, the voltage VOLT2 may be less than the
voltage VOLT1. In an embodiment, the voltage VOLT2 may be greater
than the voltage VOLT1. As noted the voltage VOLT1 may be the
ground voltage. When the voltage VOLT2 is different from the
voltage VOLT1, an electric field E-FIELD is created between the
final conductive line MF2 and the first guard ring GR1. The
electric field E-FIELD is shown to be a laterally directed electric
field through the dielectric layer DF and, in particular, through
the contaminated portion DFC of the dielectric layer DF. An
electric field E-FIELD may be created because of the potential
difference VOLT2-VOLT1. The electrical field E-FIELD may cause a
current to flow within the degraded dielectric region DFC. In the
embodiment shown in FIG. 1, the electric field E-FIELD points from
the final conductive line MF2 to the guard ring GR1. In this case,
the current flow would also be directed from the final conductive
line MF2 to the guard ring GR1. However, in another embodiment, the
electric field may point the other way from the guard ring GR1 to
the final conductive line MF2.
[0036] FIG. 2 shows an embodiment of the invention. FIG. 2 shows an
example of a lateral cross-sectional view through the cross-section
AA' of the structure 1010 shown in FIG. 1. In the embodiment shown
in FIG. 2, the first (e.g. outer) guard ring GR1 is shown to fully
encircle the final conductive line MF2. In some embodiments, the
first (e.g. outer) guard ring GR1 may at least partially (or may
fully) surround the final conductive line MF2.
[0037] It is understood that the lateral cross-section of the first
guard ring GR1 may have any shape such as rectangle, square,
triangle, circle and oval. Hence, a ring is not limited to any
particular shape. It is also understood that an encirclement by one
object of another object may form any shape such as, for example,
rectangle, square, triangle, circle and oval.
[0038] In an embodiment, the guard ring GR1 may follow the
perimeter of the structure shown in FIG. 2. In one or more
embodiments, the guard ring GR1 may be proximate the perimeter of
the structure shown in FIG. 2. In an embodiment, the structure
shown in FIG. 2 may be a semiconductor chip. It is noted that, in
one or more embodiments, the first guard ring GR1 may only
partially encircle the final conductive line MF2. Hence, the first
guard ring GR1 may at least partially encircle the final conductive
line MF2. The guard ring GR1 includes the final conductive line MF1
and may include other portions of the final metallization level
(e.g. other final conductive lines). FIG. 2 also shows the
contaminated portion DFC of the final dielectric layer DF. FIG. 2
shows the final conductive line MF2 as well as the upper conductive
pad 250 which overlies the final metal line MF2. FIG. 2 shows the
space 242A which is part of the opening 242. The space 242A permits
contaminants to contaminate the dielectric layer DF so as to create
the contaminated portion DFC of the dielectric layer DF. An
electric field E-FIELD extends from the second final conductive
line MF2 to the first final conductive line MF1. The electric field
E-FIELD passes through the contaminated portion DFC of the
dielectric layer DF.
[0039] FIG. 3 shows a semiconductor structure 1012 which is an
embodiment of the present invention. In the embodiment shown in
FIG. 3, a second guard ring GR2 is positioned as to at least
partially encircle the conductive line MF2. In one or more
embodiments, the second guard ring GR2 may fully encircle the
conductive line MF2. In an embodiment, the second guard ring GR2
may only partially encircle the conductive line MF2. In an
embodiment, the second guard ring GR2 may also be an inner guard
ring.
[0040] It is understood that the lateral cross-section of the
second guard ring GR2 may have any shape such as rectangle, square,
triangle, circle and oval. The second guard ring GR2, is not
limited to any particular shape. As noted above, an encirclement by
one object of another object may have any shape such as, for
example, rectangle, square, triangle, circle and oval.
[0041] In some embodiments, the second guard ring GR2 may at least
partially surround the conductive line MF2. In one or more
embodiments, the second guard ring GR2 may fully surround the
conductive line MF2. In some embodiments, the second guard ring GR2
may only partially surround the conductive line MF2. In an
embodiment, the second guard ring GR2 may also be an inner guard
ring.
[0042] The second guard ring GR2 may be disposed between the first
guard ring GR1 and the contaminated dielectric region DFC. In an
embodiment, the second guard ring GR2 may at least partially
encircle the contaminated region DFC. In an embodiment, the second
guard ring GR2 may partially encircle the contaminated region DFC.
In an embodiment, the second guard ring GR2 may fully encircle the
contaminated region DFC. In an embodiment, the second guard ring
GR2 may fully encircle both the final conductive line MF2 as well
as the contaminated region GR2. In an embodiment, the second guard
ring GR2 may fully encircle both the final conductive line MF2 as
well as the contaminated region DFC. In an embodiment, the second
guard ring GR2 may only partially encircle both the final
conductive line MF2 as well as the contaminated region DFC. In an
embodiment, the second guard ring GR2 may at least partially
encircle both the final conductive line MF2 as well as the
contaminated region DFC. The second guard ring GR2 may also be
referred to as an inner guard ring while the first guard ring GR1
may be referred to as an outer guard ring.
[0043] In some embodiments, the second guard ring GR2 may at least
partially surround the contaminated region DFC. In an embodiment,
the second guard ring GR2 may partially surround the contaminated
region DFC. In some embodiments, the second guard ring GR2 may
fully surround the contaminated region DFC. In some embodiments,
the second guard ring GR2 may fully surround both the final
conductive line MF2 as well as the contaminated region DFC. In some
embodiments, the second guard ring GR2 may fully surround both the
final conductive line MF2 as well as the contaminated region DFC.
In some embodiments, the second guard ring GR2 may only partially
surround both the final conductive line MF2 as well as the
contaminated region DFC. In some embodiments, the second guard ring
GR2 may at least partially surround both the final conductive line
MF2 as well as the contaminated region DFC.
[0044] In the embodiment shown, at least a portion of the second
guard ring GR2 may be part of the final metallization level MF. In
an embodiment, it is possible that the second guard ring GR2 may be
part of one or more other metallization levels. Hence, in an
embodiment, the second guard ring GR2 may include one or more
conductive lines belonging to the final metallization level. In an
embodiment, the second guard ring GR2 may include one or more
conductive lines belonging to one or more of the other
metallization levels. In an embodiment, the second guard ring GR2
may include one or more conductive vias.
[0045] The second guard ring GR2 may be electrically coupled to the
conductive line MF2. Hence, it is possible that the voltage of the
second guard ring GR2 is the same as the voltage of the conductive
line MF2. Electrical coupling may be accomplished by other
conductive lines and/or vias. The conductive lines that do the
electrical coupling may be located on the same metallization level
(for example, final metallization level) as the second guard ring
GR2 and the conductive line MF2 or a different metallization level
as the second guard ring GR2 and the conductive line MF2. As an
example, electrical coupling may be accomplished by one or more
other final conductive lines which are part of the final
metallization level. As another example, electrical coupling may be
accomplished by at least one conductive line that is part of
another metallization level. Electrical coupling may also be
accomplished by one or more conductive vias (and possibly in
combination with one or more conductive lines). Electrical coupling
may also be accomplished using a redistribution layer above the
final metallization level.
[0046] The second guard ring GR2 may be positioned so that it is
between the contaminated portion DFC of the dielectric layer DF and
the first guard ring GR1.
[0047] By electrically coupling the second guard ring GR2 to the
conductive line MF2, the second guard ring GR2 may be at the same
voltage as the conductive line MF2. Hence, there may be no voltage
difference and no lateral electrical field between the conductive
line MF2 and the second guard ring GR2. Hence, there may be
substantially no (or no) electric field. In an embodiment, there
may be substantially no (or no) electric field within the
contaminated region DFC. In particular, in an embodiment, there may
be substantially no (or no) laterally directed electric field
within the contaminated region DFC. In an embodiment, there may be
substantially no (or no) electric field proximate the conductive
line MF2. In an embodiment, there may be substantially no (or no)
laterally directed electric field proximate the second conductive
line MF2. Hence, there may be substantially no (or no) current flow
within the contaminated region DFC. There may still be a voltage
difference VOLT2-VOLT1 and a lateral electric field E-FIELD outside
the contaminated region DFC. However, this may not be a problem
since the dielectric strength of the non-contaminated portion of
the dielectric layer DF may still be good in this region. Hence,
while not wishing to be bound by theory, it is possible that the
second guard ring GR2 may help to alleviate the problem caused by
the space 242A and the contaminated portion DFC of the dielectric
layer DF.
[0048] FIG. 4 shows an example of a lateral cross-sectional view
through the cross-section AA' of the structure 1012 from FIG. 3. In
the embodiment shown in FIG. 4, the second guard ring GR2 is shown
to fully encircle the final conductive line MF2 as well as the
contaminated portion DFC. However, in other embodiments, the second
guard ring GR2 may partially encircle the first guard ring GR1 and
may partially encircle the contaminated region DFC. Hence, the
second guard ring GR2 may at least partially encircle the first
guard ring GR1 and may at least partially encircle the contaminated
portion DFC. In an embodiment, the second guard ring GR2 may be
positioned so that substantially no electric field or no electrical
field (for example, substantially no lateral electric field or no
lateral electric field) passes through the contaminated portion
DFC. In one or more embodiments, the second guard ring GR2 may be
position between the first guard ring GR1 and the conductive line
MF2. In one or more embodiments, second guard ring GR2 may be
positioned between the first guard ring GR1 and the contaminated
portion DFC.
[0049] In some embodiments, the second guard ring GR2 may fully
surround the final conductive line MF2 as well as the contaminated
portion DFC. However, in other embodiments, the second guard ring
GR2 may partially surround the first guard ring GR1 and may
partially surround the contaminated region DFC. Hence, the second
guard ring GR2 may at least partially surround the first guard ring
GR1 and may at least partially surround the contaminated portion
DFC. In an embodiment, the second guard ring GR2 may be positioned
so that substantially no electric field or no electrical field (for
example, substantially no lateral electric field or no lateral
electric field) passes through the contaminated portion DFC. In one
or more embodiments, the second guard ring GR2 may be position
between the first guard ring GR1 and the conductive line MF2. In
one or more embodiments, second guard ring GR2 may be positioned
between the first guard ring GR1 and the contaminated portion
GR1.
[0050] FIG. 4 shows that, in an embodiment, the electrical coupling
between the second guard ring GR2 and the conductive line MF2 may
be accomplished using the electrical coupling 260. The electrical
coupling 260 may be part of the final metallization level (for
example, it may be a final conductive line). However, the
electrical coupling between the second guard ring GR2 and the final
metal line MF2 may be accomplished in any way.
[0051] With the second guard ring GR2 in place, an electric field
E-FIELD extends from the second guard ring GR2 to the first guard
ring GR1 but there may be substantially no (or no) electric field
through the contaminated portion DFC of the dielectric layer DF. In
particular, there may be substantially no (or no) laterally
directed electric field through the contaminated portion DFC of the
dielectric layer DF.
[0052] The embodiments shown in FIGS. 1 through 4 show a final
conductive line MF2. The final conductive line MF2 may have any
shape. In one or more embodiments, the conductive line MF2 may be
replaced with an conductive feature. In an embodiment, the final
conductive line MF2 may be in the shape of a coil. FIG. 5 shows a
structure 1014 which is a lateral cross-section of an embodiment
wherein the final conductive line MF2 may be in the shape of a coil
610U. In the embodiment shown in FIG. 5, the coil 610U is a spiral
coil. In other embodiments, the coil 61U may be replaced with a
loop coil. The coil 610U may include a pad portion P.
[0053] The coil 610U may be one of the coils of a transformer, such
as a coreless transformer. FIG. 6 shows a structure 1016. The
structure 1016 shown in FIG. 6 may, for example, represent a
vertical cross-section of the structure 1014 shown in FIG. 5.
Likewise, the structure 1014 shown in FIG. 5 may, for example,
represent a horizontal cross-section through the cross-section AA'
shown in FIG. 6.
[0054] Referring to the structure 1016 shown in FIG. 6, it is seen
that the coil 610U may be the upper coil of a transformer 610. The
transformer 610 may also include a lower coil 610L. The transformer
610 may be a coreless transformer. In an embodiment, the upper coil
may be at a higher voltage than the lower coil. In an embodiment,
the lower coil may be at a higher voltage than the upper coil. The
upper coil 610U may include a pad portion P that is used to
electrically couple to a probe or to bond wire 310 that is shown in
FIG. 6.
[0055] Referring to FIGS. 5 and 6, in some embodiments, the first
guard ring GR1 may at least partially encircle the upper coil 610U.
In some embodiments, the first guard ring GR1 may fully encircle
the upper coil 610U. In some embodiments, the first guard ring GR1
may at least partially encircle the transformer 610. In some
embodiments, the first guard ring GR1 may fully encircle the
transformer 610.
[0056] In some embodiments, the second guard ring GR2 may fully
encircle the upper coil 610U. In some embodiments, the second guard
ring GR2 may at least partially encircle the transformer 610. In
some embodiments, the second guard ring GR2 may fully encircle the
transformer 610.
[0057] In some embodiments, the first guard ring GR1 may at least
partially surround the upper coil 610U. In some embodiments, the
first guard ring GR1 may fully surround the upper coil 610U. In
some embodiments, the first guard ring GR1 may at least partially
surround the transformer 610. In some embodiments, the first guard
ring GR1 may fully surround the transformer 610.
[0058] In some embodiments, the second guard ring GR2 may fully
surround the upper coil 610U. In some embodiments, the second guard
ring GR2 may at least partially surround the transformer 610. In
some embodiments, the second guard ring GR2 may fully surround the
transformer 610.
[0059] Referring to FIG. 5, it is seen that the second guard ring
GR2 may be electrically coupled to the upper coil 610U using an
electrical coupling 260. The electrical coupling 260 may be part of
the final metallization level. The electrical coupling 260 placing
the second guard ring GR2 and the upper coil 610U at the same
voltage.
[0060] Hence, the ideas presented herein are also applicable to
coils as well as to transformers such as coreless transformers.
Referring again to FIG. 5 and to FIG. 6, it is seen that a
semiconductor structure may include a transformer 610 that includes
an upper coil 610U and a lower coil 610L. In some embodiments, a
first guard ring GR1 which may fully encircle the upper coil 610U.
In another embodiment, the first guard ring GR1 may partially
encircle the upper coil 610U. Hence, the first guard ring GR1 may
at least partially encircle the upper coil 610U. In some
embodiments, a second guard ring GR2 may fully encircle the upper
coil 610U. In some embodiments, the second guard ring GR2 may
partially encircle the upper coil 610U. Hence, the second guard
ring GR2 may at least partially encircle the upper coil 610U.
[0061] Referring to FIGS. 5 and 6, in some embodiments, a first
guard ring GR1 which may fully surround the upper coil 610U. In
some embodiments, the first guard ring GR1 may surround the upper
coil 610U. In some embodiments, the first guard ring GR1 may at
least partially surround the upper coil 610U. In some embodiments,
a second guard ring GR2 may fully surround the upper coil 610U. In
some embodiments, the second guard ring GR2 may partially surround
the upper coil 610U. In some embodiments, the second guard ring GR2
may at least partially surround the upper coil 610U.
[0062] The structure 1014 includes a final metallization level MF
that is embedded in a dielectric layer DF. The dielectric layer DF
includes a contaminated portion DFC.
[0063] Referring to FIGS. 5 and 6, the upper coil 610U may be part
of the final metallization level MF. An upper bond pad 250 overlies
the upper coil 610U. In particular, the upper bond pad 250 may
overlie the pad portion P of the upper coil 610U.
[0064] It is noted that the second guard ring GR2 may help to
improve the reliability of the transformer 610 that is shown in
FIG. 6.
[0065] Any of the conductive lines and/or conductive layers and/or
conductive vias and/or guard rings and/or conductive features (for
example, coils and/or transformers) discussed herein may include
any conductive material. The conductive material may, for example,
include a metallic material. In one or more embodiment, a
conductive material may include at least one element selected from
the group consisting of Cu (copper), Al (aluminum), Au (gold), Ag
(silver), and W (tungsten). A conductive material may include a
pure metal and/or a metal alloy. It is understood that any pure
metal may include trace impurities. In one or more embodiments, a
conductive material may include at least one material selected from
the group consisting of pure copper, copper alloy, pure aluminum,
aluminum alloy, pure gold, gold alloy, pure silver, silver alloy,
pure tungsten, and tungsten alloy.
[0066] FIGS. 7A and 7B show a side perspective view and a top view
respectively of a conductive feature according to various
embodiments. The conductive feature may include a transformer 610,
such as the transformer 610 described with respect to structure
1016. The transformer 610 may include upper coil 610U of the
transformer 610. The transformer 610 may also include lower coil
610L of the transformer 610. From the top view as shown in FIG. 7B,
upper coil 610U of the transformer 610 is shown. Upper coil 610U
may include a first spiral coil 612A and a second spiral coil 612B.
First spiral coil 612A and second spiral coil 612B may include one
or more spirals or windings, such as a plurality of spirals or
windings. A first end of first spiral coil 612A disposed at the
center or eye of first spiral coil 612A may include a first
electrically conductive pad 650A. A middle pad MPU may connect a
second end of first spiral coil 612A to a second end of second
spiral coil 612B. A first end of second spiral coil 612B disposed
at the center or eye of second spiral coil 612B may include a
second electrically conductive pad 650B. The middle pad MPU may be
disposed between the first spiral coil 612A and the second spiral
coil 612B.
[0067] Even though the middle pad MPU may be disposed between the
first spiral coil 612A and the second spiral coil 612B, the middle
pad MPU may not be enclosed by first spiral coil 612A and the
second spiral coil 612B.
[0068] The transformer 610 may be a part of a structure, such as
structure 1018 described in FIG. 8. The upper coil 610U may form
part of or be the final conductive line MF2 in an embodiment. The
first guard ring GR1 may at least partially encircle the final
conductive line MF2, i.e. the upper coil 610U in an embodiment. As
an example, the first guard ring GR1 may at least partially
encircle the conductive feature, such as at least one of the upper
coil 610U and the lower coil 610L of transformer 610. In an
embodiment, the first guard ring GR1 may fully encircle the final
conductive line MF2. For example, as shown in FIG. 7B, the first
guard ring GR1 may form a closed loop around upper coil 610U and/or
the lower coil 610L. In an embodiment, instead of fully encircling
the upper coil 610U, the first guard ring GR1 may only partially
encircle the upper coil 610U and/or lower coil 610L.
[0069] FIG. 8 shows a structure 1018 according to an embodiment.
The structure 1018 shown in FIG. 8 may include the conductive
feature, such as transformer 610. FIG. 8 shows a horizontal
cross-section BB' taken through the upper middle pad MPU of upper
coil 610U, and through a lower middle pad MPL of the lower coil
610L.
[0070] The structure 1018 may also include the first guard ring GR1
which may at least partially surround upper coil 610U and lower
coil 610L.
[0071] In some embodiments, lower coil 610L may be placed at chip
potential, e.g. VOLT1, which may be a ground potential. Upper coil
610U may be placed at a high potential, e.g. VOLT2, which may be
for example about 10 kV. First guard ring GR1 may be placed at
VOLT1, in other words at the potential of lower coil 610L.
[0072] Without a second guard ring GR2, similar complexities as
described according to FIG. 1 may occur. Due to a difference
between voltage VOLT2 and voltage VOLT1, an electric field E-FIELD
may be created. The electric field E-FIELD may be formed between
the upper middle pad MPU of upper coil 610U, which may be placed at
VOLT1, e.g. 10 kV, and the first guard ring GR1. For example, the
electric field E-FIELD may be laterally directed through the
dielectric layer DF and, in particular, through the contaminated
portion DFC of the dielectric layer DF. In other words, the upper
middle pad MPU of upper coil 610U sees the potential of the first
guard ring GR1.
[0073] As shown in the structure 1018, a second guard ring GR2, may
be included in the structure 1018. The second guard ring GR2 may
partially encircle the middle pad MPU. Furthermore, the second
guard ring GR2 may at least partially encircle the contaminated
region DFC.
[0074] FIGS. 9A to 9C show various ways in which the second guard
ring GR2 may be implemented in structure 1018.
[0075] In one embodiment, as shown in FIG. 9A, the second guard
ring GR2 may partially encircle upper coil 610U. The second guard
ring GR2 may be disposed between upper coil 610U and the first
guard ring GR1. The second guard ring GR2 may be disposed between
contaminated region DFC and the first guard ring GR1. The
contaminated region DFC may be in the surrounding region, e.g. in
the adjacent regions, of upper coil 610U. The contaminated region
DFC may be in the surrounding region of middle pad MPU.
[0076] The second guard ring GR2 may also shield middle pad MPU
from first guard ring GR1. For example, at least part of the second
guard ring GR2 may be disposed between the middle pad MPU and the
first guard ring GR1. The second guard ring GR2 may be in the form
of an open loop ring which encircles upper coil 610U. The second
guard ring GR2 may be structured in a shape which traces the outer
perimeter of upper coil 610U. In other words, second guard ring GR2
may be disposed around the perimeter of upper coil 610U at a
substantially uniform distance apart from the outermost coil or
winding of upper coil 610U.
[0077] The second guard ring GR2 may be electrically coupled to the
middle pad MPU, in other words, the second guard ring GR2 may be
placed at the same voltage as middle pad MPU. This may mean that
second guard ring GR2 may be electrically coupled to have the same
voltage as middle pad MPU. For example, the second guard ring GR2
may even be electrically coupled to the outermost coil or winding
of the upper coil 610U. However, the second guard ring GR2 may be
left open ended, i.e. not closed, to prevent induction of
electrical current in the ring, which, in turn, may cause a
magnetic field which may counteract the magnetic field of the upper
coil 610U. The second guard ring GR2 may be buried in an insulation
layer, e.g. dielectric layer DF, which may include an oxide or a
nitride. The middle pad MPU may be exposed for bonding. The upper
conductive pad 250 may be formed over the middle pad MPU.
[0078] FIG. 9A shows a structure of the second guard ring GR2
according to an embodiment. The second guard ring GR2 may have a
first end electrically coupled or connected to the middle pad MPU.
The second guard ring
[0079] GR2 may have a second end electrically isolated from the
middle pad MPU, and distally separated from the first end of the
middle pad MPU. The second guard ring GR2 may encircle or surround
only part of the upper coil 610U, and at least part of the upper
coil 610U may not be encircled by the second guard ring GR2.
[0080] FIG. 9B shows a structure of the second guard ring GR2
according to another embodiment, wherein the first end and the
second end of the second guard ring GR2 may at least partially
overlap. Despite overlapping, the first end and the second end are
open. In other words, the first end and the second end do not form
a closed ring.
[0081] FIG. 9C shows a structure of the second guard ring GR2
according to another embodiment. The second guard ring GR2 may
include one or more sets of curved arms. As shown in FIG. 9C, the
second guard ring GR2 may include two sets of curved arms, ARM1 and
ARM2. Each set of curved arms ARM1 and ARM2 may include one or a
plurality of curved arms. In an embodiment shown in FIG. 9C, each
set of curved arms ARM1 and ARM2 may include two curved arms. It
may be understood that each set of curved arms ARM1 and ARM2 may
not be limited to two but may include only one curved arm or even
more than two curved arms. The sets of curved arms ARM1 and ARM2
may be arranged to shield the middle pad MPU from the first guard
ring GR1. As an example, one set of curved arms ARM1 may encircle a
first part of an outer perimeter of middle pad MPU, and may be
disposed between the first part and the first guard ring GR1.
Another set of curved arms ARM2 may encircle a second part of an
outer perimeter of middle pad MPU, and may be disposed between the
second part and the first guard ring GR1. Each set of curved arms
ARM1 and ARM2 may have a handlebar shape. Each set of curved arms
ARM1 and ARM2 may have a first end electrically coupled to the
middle pad MPU. Each set of curved arms ARM1 and ARM2 may have a
second end which is not electrically coupled to the middle pad MPU,
i.e. electrically isolated from middle pad MPU. The second ends of
each set of curved arms ARM1 and ARM2 may be rounded. The rounded
end portions CR of the curved arms ARM1 and ARM2 may avoid or
reduce electric field peaks.
[0082] FIG. 10 shows transformer 610 according to an embodiment. In
an embodiment, transformer 610 may include the upper coil 610U and
the lower coil 610L (not shown). However, each of the upper coil
610U and the lower coil 610L may only include a single spiral coil
612. FIG. 10 shows a top view of upper coil 610U having single
spiral coil 612. First electrically conductive pad 650A may be
disposed at the eye or center of single spiral coil 612. Middle pad
MPU may be electrically coupled to the outermost coil or winding of
upper coil 610U. A second guard ring GR2 may be electrically
coupled at one end to a part of the structure which may be at the
same potential as the middle pad MPU. As an example, the second
guard ring GR2 may be electrically coupled to the outermost coil or
winding of upper coil 610U and/or to the middle pad MPU. The second
guard ring GR2 may encircle the middle pad MPU, however may remain
open-ended. In other words, the second guard ring GR2 may not form
a closed electrical loop.
[0083] One or more embodiments relate to a semiconductor structure,
including: a conductive feature; an outer guard ring; and an inner
guard ring between the outer guard ring and the conductive feature,
the inner guard ring being at the same voltage as the conductive
feature.
[0084] According to one or more embodiments, the outer guard ring
at least partially encircles the conductive feature.
[0085] According to one or more embodiments, the inner guard ring
at least partially encircles the conductive feature.
[0086] According to one or more embodiments, the inner guard ring
partially encircles the conductive feature.
[0087] According to one or more embodiments, the inner guard ring
fully encircles the conductive feature.
[0088] According to one or more embodiments, the conductive feature
is part of a final metallization level.
[0089] According to one or more embodiments, the conductive feature
is a conductive coil.
[0090] According to one or more embodiments, the conductive feature
is a transformer, the transformer including an upper coil over a
lower coil.
[0091] According to one or more embodiments, the inner guard ring
is part of a final metallization level.
[0092] According to one or more embodiments, the said outer guard
ring is proximate the periphery of the semiconductor structure.
[0093] According to one or more embodiments, the conductive feature
is embedded in a dielectric layer, the dielectric layer including a
contaminated portion between the outer guard ring and the
conductive feature.
[0094] According to one or more embodiments, the inner guard ring
is positioned so that there is substantially no lateral electric
field through the contaminated portion.
[0095] According to one or more embodiments, the inner guard ring
is between said outer guard ring and the contaminated portion.
[0096] According to one or more embodiments, a resistivity of the
contaminated portion is less than a resistivity of a
non-contaminated portion of the dielectric layer.
[0097] According to one or more embodiments, the conductive feature
is a capacitor.
[0098] According to one or more embodiments, the conductive feature
is a capacitor, the capacitor including an upper capacitor plate
over a lower capacitor plate.
[0099] One or more embodiments relate to a semiconductor structure,
including: a conductive feature; an outer guard ring; and
an inner guard ring between the outer guard ring and the conductive
feature, the inner guard ring being electrically coupled to the
conductive feature.
[0100] According to one or more embodiments, the outer guard ring
at least partially encircles the conductive feature.
[0101] According to one or more embodiments, the inner guard ring
at least partially encircles the conductive feature.
[0102] According to one or more embodiments, the conductive feature
is part of a final metallization level.
[0103] According to one or more embodiments, the conductive feature
is a conductive coil.
[0104] According to one or more embodiments, the conductive feature
is a transformer, the transformer including an upper coil over a
lower coil.
[0105] According to one or more embodiments, the inner guard ring
is part of a final metallization level.
[0106] According to one or more embodiments, the outer guard ring
is proximate the periphery of the semiconductor structure.
[0107] According to one or more embodiments, the conductive feature
is embedded in a dielectric layer, the dielectric layer including a
contaminated portion between the outer guard ring and the
conductive feature.
[0108] According to one or more embodiments, the inner guard ring
is positioned so that there is substantially no lateral electric
field in the contaminated portion.
[0109] According to one or more embodiments, the inner guard ring
is positioned so that there is substantially no current in the
contaminated portion.
[0110] According to one or more embodiments, the inner guard ring
is between the outer guard ring and the contaminated portion.
[0111] According to one or more embodiments, a resistivity of the
contaminated portion is less than a resistivity of a
non-contaminated portion.
[0112] According to one or more embodiments, the conductive feature
is a capacitor.
[0113] According to one or more embodiments, the conductive feature
is a capacitor, the capacitor including an upper capacitor plate
over a lower capacitor plate.
[0114] One or more embodiments relate to a semiconductor structure,
including: a dielectric layer the dielectric layer having a
contaminated portion; a conductive feature disposed in the
dielectric layer, the conductive feature being at a first voltage;
and an outer guard ring disposed in the dielectric layer, the outer
guard ring being at a second voltage different from the first
voltage, wherein there is substantially no lateral electric field
proximate the conductive feature.
[0115] One or more embodiments relate to a semiconductor structure,
including: a dielectric layer the dielectric layer having a
contaminated portion; a conductive feature disposed in the
dielectric layer, the conductive feature being at a first voltage;
and an outer guard ring disposed in the dielectric layer, the outer
guard ring being at a second voltage different from the first
voltage, wherein there is substantially no lateral electric field
within the contaminated portion.
[0116] According to one or more embodiments, the semiconductor
structure further includes an inner guard ring between said outer
guard ring and said contaminated portion.
[0117] According to one or more embodiments, outer guard ring at
least partially encircles the conductive feature. According to one
or more embodiments, the inner guard ring at least partially
encircles the conductive feature.
[0118] According to one or more embodiments, the conductive feature
is part of a final metallization level.
[0119] According to one or more embodiments, the conductive feature
is a conductive coil.
[0120] According to one or more embodiments, the conductive feature
is a transformer, the transformer including an upper coil over a
lower coil.
[0121] According to one or more embodiments, the inner guard ring
is part of a final metallization level.
[0122] According to one or more embodiments, the contaminated
portion has a resistivity less than a remaining portion of said
dielectric layer.
[0123] According to one or more embodiments, the conductive feature
is a capacitor.
[0124] According to one or more embodiments, the conductive feature
is a capacitor, the capacitor including an upper capacitor plate
over a lower capacitor plate.
[0125] One or more embodiments relate to a semiconductor structure,
including: a conductive feature; an outer guard ring; and an inner
guard ring between said outer guard ring and the conductive
feature, said outer guard ring being at the same voltage as the
conductive feature.
[0126] One or more embodiments relate to a semiconductor structure,
including: a conductive feature; an outer guard ring; and an inner
guard ring between the outer guard ring and said conductive
feature, said inner guard ring being electrically coupled to the
conductive feature.
[0127] One or more embodiments relate to a semiconductor structure,
including: a dielectric layer the dielectric layer having a
corrupted portion; a conductive feature disposed in said dielectric
layer, the conductive feature being at a first voltage; and an
outer guard ring disposed in said dielectric layer, the outer guard
ring being at a second voltage different from said first voltage,
wherein there is substantially no lateral electric field within the
corrupted portion.
[0128] One or more embodiments relate to a semiconductor structure,
including: a dielectric layer the dielectric layer having a
corrupted portion; a conductive feature disposed in the dielectric
layer, the conductive feature being at a first voltage; and an
outer guard ring disposed in the dielectric layer, the outer guard
ring being at a second voltage different from said first voltage,
wherein there is substantially no lateral electric field proximate
the conductive feature.
[0129] The disclosure herein is presented in the form of detailed
embodiments described for the purpose of making a full and complete
disclosure of the present invention, and that such details are not
to be interpreted as limiting the true scope of this invention as
set forth and defined in the appended claims.
* * * * *